Confirmation of linear system theory prediction: Changes in Herrnstein's k as a function of changes in reinforcer magnitude

Eight human subjects pressed a lever on a range of variable-interval schedules for 0.25¢ to 35.0¢ per reinforcement. Herrnstein's hyperbola described seven of the eight subjects' response-rate data well. For all subjects, the y-asymptote of the hyperbola increased with increasing reinforcer magnitude and its reciprocal was a linear function of the reciprocal of reinforcer magnitude. These results confirm predictions made by linear system theory; they contradict formal properties of Herrnstein's account and of six other mathematical accounts of single-alternative responding.     

Choice in a "self-control" paradigm: effects of a fading procedure

Pigeons chose between an immediate 2-second reinforcer (access to grain) and a 6-second reinforcer delayed 6 seconds. The four pigeons in the control group were exposed to this condition initially. The four experimental subjects first received a condition where both reinforcers were delayed 6 seconds. The small reinforcer delay was then gradually reduced to zero over more than 11,000 trials. Control subjects almost never chose the large delayed reinforcer. Experimental subjects chose the large delayed reinforcer significantly more often. Two experimental subjects showed preference for the large reinforcer even when the consequences for pecking the two keys were switched. The results indicate that fading procedures can lead to increased “self-control” in pigeons in a choice between a large delayed reinforcer and a small immediate reinforcer.     

Choice behavior of rats in a concurrent-chains schedule: Amount and delay of reinforcement

Rats were exposed to concurrent-chains schedules in which the terminal links were equal fixed-interval schedules terminating in one or three food pellets. Choice proportions for large reward increased with increases in delay intervals programmed on fixed-interval schedules and supported the predictions derived from a general choice model originally formulated by Fantino and later developed by Navarick and Fantino. In addition, a functional equivalence of two alternatives was established by increasing delay intervals with large reward, whereas delay intervals for small reward were held constant. Functionally equivalent delay intervals with large reward, for each delay interval with small reward, can be described by a power function with exponent smaller than 1.0. A better prediction of choice proportions resulted when this function was used to derive predicted choice proportions.     

Autoshaped key pecking maintained by access to a social space.

When four experimentally naive pigeons were exposed to occasional forward pairings of a keylight followed by a doorlight (that signaled access to a large social space), all subjects began to peck the lit key. In a second experiment, where the keylight either preceded the presentation of the doorlight or was presented independently of it, key pecking was maintained only in the former circumstance. The unconditioned stimulus in these experiments--arrival in the social space--did not elicit pecking. Hence, the conditioned response of key pecking and the unconditioned response of entering the social space differed. This demonstration of autoshaping with a social-space unconditioned stimulus argues against a stimulus-substitution account of the findings.     

中学生阅读动机与阅读时间、阅读成绩的关系研究

采用问卷调查法对３５３名初、高中学生的阅读动机、阅读时间及阅读成绩进行了调查,结果发现：１．中学生的阅读动机是多维度的,包括内部动机、外部动机、社会性动机与自我效能,它们之间相互影响、相互联系;２．中学生阅读动机水平的高低与阅读时间、阅读成绩存在极为显著的正相关,其中,内部动机对中学生阅读时间、阅读成绩的影响要大于其它因素的影响;３．中学生的阅读动机发展特点具有性别帮年级差异,趋势是初中生优于高中     

Effects of stimulus variation on the reinforcing capability of nonpreferred stimuli

We examined the effects of stimulus (reinforcer) variation in several different contexts. In Study 1, we identified high-quality (HQ) and low-quality (LQ) stimuli based on results of a paired-stimulus assessment and examined their effects when available under concurrent-reinforcement schedules for 8 participants. No participants showed preference for the LQ stimuli when compared singly or in a varied arrangement to the HQ stimulus. In Study 2, we identified nonpreferred (NP) stimuli based on results of a single-stimulus assessment and examined their effects when available under single-reinforcement schedules for 3 participants. Results of Study 2 were mixed. One participant's data indicated that the varied presentation of NP stimuli produced a modest improvement in performance over that observed when the stimuli were presented singly. By contrast, a second participant's data showed no facilitative effect for the varied delivery of NP stimuli and that the inclusion of an HQ stimulus in the varied arrangement obscured the reinforcing effects of the HQ stimulus. The 3rd participant's data showed no effect for the varied delivery of NP stimuli but an apparent facilitative effect when an HQ stimulus was included in the varied arrangement, which was attributable solely to the presence of the HQ stimulus.